A semiconductor light emitting device 51 shown in FIG. 15, comprises a support 1, LED chips 2 as semiconducting light emitting elements secured on support 1, and a light transmitting protective resin 5 for encapsulating LED chips 2. The light emitting device 51 of this kind is known by U.S. patent application published under 2005/0236638 presented by the same inventor of this patent application and published Oct. 27, 2005. Support 1 comprises four side walls 35 for forming light reflecting surfaces 9, a bottom wall 36 connected to side walls 35 for a mount surface 33a between light reflecting surfaces 9, and a channel 33 surrounded by light reflecting surfaces 9 above bottom wall 36 to form a horizontal opening 37 at the top of channel 33. LED chips 2 are secured on mount surface 33a of support 1 and surrounded by side walls 35 of support 1. Each light reflecting surface 9 defined by longitudinal side walls 35 has an upwardly divergent ramp of light reflectivity for improvement in directivity and front brightness of light from LED chips 2.
For example, a back light of display in cellular phone, etc., employs a linear light source which comprises a plurality of semiconductor light emitting units connected in line to each other. FIG. 16 demonstrates a linear light source 61 having a plurality of semiconductor light emitting units or devices 51 longitudinally coupled to each other. Each semiconductor light emitting device 51 has eight LED chips 2 longitudinally arranged in line. Linear light source 61 shown in FIG. 16 can change the number of semiconductor light emitting devices 51 to be coupled to easily vary the length of linear light source 61 for different light source dimension in response to the requirement to size alteration in necessary display.
However, linear light source 61 of FIG. 16 is defective because its brightness is rather low in each join portion 21 connecting between semiconductor light emitting devices 51 due to insufficient amount of light from LED chips 2 even though light 20 is irradiated outside from LED chips 2 through horizontal opening 37 of support 1. Specifically, lateral side or end walls 35 of adjacent semiconductor light emitting device 51 obstruct path of light 20 emitted from LED chips 2 to outside in the lengthwise apposed construction of plural semiconductor light emitting devices 51. In this way, linear light source 61 of plural semiconductor light emitting devices 51 cannot uniformly release light along the longitudinal direction of light source 61.
Meanwhile, Japanese Patent Disclosure No. 2000-91646 published Mar. 31, 2000 represents a semiconductor light emitting device which comprises a support, a plurality of LED chips mounted on support in line, and light-reflectors attached around LED chips near both ends of support to increase amount of released light. This semiconductor light emitting device was considered to be able to repress brightness deterioration at the join portion between both ends of each semiconductor light emitting device by increase in front brightness of light irradiated from LED chips to outside.
Nevertheless, reflective structure shown in the latter Japanese reference cannot be applied to the reflective structure of the device 51 shown in FIG. 15 due to the difference in structure because the latter Japanese reference shows reflectors attached only to LED chips around both ends of support, whereas FIG. 15 displays a side wall 35 throughout the entire periphery of support 1. Also, even the semiconductor light emitting device of the latter reference cannot satisfactorily improve brightness deterioration between LED chips. Accordingly, it is unrealistic to utilize the light emitting structure shown in the latter reference to adjust brightness of light from LED chips near both ends of support for accomplishment of uniformly irradiated light along the longitudinal direction of linear light source.
Therefore, an object of the present invention is to provide a semiconductor light emitting unit which can assemble, by combination of plural light emitting units, a linear light source capable of producing lengthwise uniform light, method for manufacturing the same and linear light source.